Methods for replacing nuggeted combustor liner panels

ABSTRACT

A replacement method facilitates replacing of a portion of a nuggeted combustor liner within a gas turbine engine combustor in a cost-effective and reliable manner. The combustor includes a combustion zone that is defined by an inner and an outer liner. The inner and outer liners each include a series of panels and a plurality of nuggets formed by adjacent panels. The method includes the steps of cutting between an outer surface and an inner surface of at least one liner panel through at least one nugget, removing at least one panel that is adjacent the area of the liner that was cut, and installing a replacement panel into the combustor for each panel that was removed from the combustor.

BACKGROUND OF THE INVENTION

[0001] This invention relates generally to gas turbine engine, and moreparticularly, to methods for replacing nuggeted combustor liner panelsused with gas turbine engines.

[0002] A turbine engine includes a compressor for compressing air whichis mixed with a fuel and channeled to a combustor wherein the mixture isignited within a combustion chamber for generating hot combustion gases.At least some known combustors include a dome assembly, a bolt banding,and liners to channel the combustion gases to a turbine, which extractsenergy from the combustion gases for powering the compressor, as well asproducing useful work to propel an aircraft in flight or to power aload, such as an electrical generator. The liners are coupled to thedome assembly with the bolt banding, and extend downstream from the boltbanding to define the combustion chamber.

[0003] At least some known liners include a plurality of panels that areconnected together with riveted, bolted, or welded connections. Aportion of the panels include cooling nuggets formed between adjacentpanels, that extend radially outwardly from the panels and away from thecombustion chamber. Accordingly, such cooling nuggets are not subjectedto the same degree of heat as portions of the panels adjacent thecombustion chamber, and as such, during operation thermal stresses maybe induced within the panels. Over time, continued operation withthermal stresses may cause panels to thermally fatigue, causingweakening and/or cracking to develop within the panels.

[0004] Current repair methods include welding thermal fatigue cracks.Additionally, patches may be attached to areas of panels that areweakened by thermal stresses. However, if the thermal stresses haveinduced thermal fatigue or distress in larger areas of the panels or ina plurality of panels, the combustor may not have enough structuralintegrity within such panels to enable patches to be attached. In suchcases, repair of such panels is not a feasible option, and instead theentire combustor liner is replaced. Because the liner is coupled to thebolt band and the dome assembly, often the entire combustor must bedisassembled for the liner to be replaced. Furthermore, when thefasteners are removed from the bolt band and dome assembly, precisedimensional relations between the components may be altered and as aresult, special tooling may be required during re-assembly. Thus,replacing a combustor liner including cooling nuggets may be atime-consuming and expensive process.

BRIEF SUMMARY OF THE INVENTION

[0005] In an exemplary embodiment, a method facilitates replacing aportion of a nuggeted combustor liner within a gas turbine enginecombustor in a cost-effective and reliable manner. The combustorincludes a combustion zone that is defined by an inner and an outerliner. The inner and outer liners each include a series of panels and aplurality of nuggets formed by adjacent panels. A plurality of thepanels include cooling nuggets. The method includes the steps of cuttingthrough at least one panel nugget to remove at least one panel from thecombustor, and installing at least one replacement panel into thecombustor such that the series of panels are arranged in steps relativeto one another.

[0006] In another aspect of the invention, a method is used to replaceat least one deteriorated combustor liner panel within a gas turbineengine combustor that includes an annular liner including a multinuggetregion, a mulithole region, an inner surface, and a plurality ofnuggets. The method includes the steps of cutting through at least onenugget downstream from the at least one deteriorated combustor linerpanel to be replaced and within at least one of the liner multinuggetregion and the liner multihole region, removing the at least onedeteriorated combustor liner panel from the combustor, and welding atleast one replacement panel to at least one existing panel within thecombustor for each deteriorated combustor liner panel removed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is schematic illustration of a gas turbine engine;

[0008]FIG. 2 is a partial cross-sectional view of a combustor assemblythat may be used with the gas turbine engine shown in FIG. 1;

[0009]FIG. 3 is an enlarged view of a combustor liner used with thecombustor shown in FIG. 2 taken along area 3;

[0010]FIG. 4 is an enlarged cross-sectional view of an alternativeembodiment of a combustor liner that may be used with the gas turbineengine shown in FIG. 1; and

[0011]FIG. 5 is an enlarged plan view of the combustor liner shown inFIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

[0012]FIG. 1 is a schematic illustration of a gas turbine engine 10including a low pressure compressor 12, a high pressure compressor 14,and a combustor 16. Engine 10 also includes a high pressure turbine 18and a low pressure turbine 20. Compressor 12 and turbine 20 are coupledby a first shaft 22, and compressor 14 and turbine 18 are coupled by asecond shaft 21. In one embodiment, gas turbine engine 10 is a GE90engine commercially available from General Electric Aircraft Engines,Cincinnati, Ohio. In another embodiment, gas turbine engine 10 is a CFengine commercially available from General Electric Aircraft Engines,Cincinnati, Ohio.

[0013] In operation, air flows through low pressure compressor 12 andcompressed air is supplied from low pressure compressor 12 to highpressure compressor 14. The highly compressed air is delivered tocombustor 16. Airflow from combustor 16 drives turbines 18 and 20 andexits gas turbine engine 10 through a nozzle 24.

[0014]FIG. 2 is a partial cross-sectional view of a combustor 30. FIG. 3is an enlarged view of a portion of combustor 30. Combustor 30 may beused with gas turbine engine 10 shown in FIG. 1, and includes a domeassembly 32. A fuel injector (not shown) extends into dome assembly 32and injects atomized fuel through dome assembly 32 into a combustionzone 36 of combustor 30 to form an air-fuel mixture that is igniteddownstream of the fuel injector

[0015] Combustion zone 36 is formed by annular, radially outer andradially inner supporting members (not shown) and combustor liners 40.Combustor liners 40 shield the outer and inner supporting members fromthe heat generated within combustion zone 36 and includes an inner liner42 and an outer liner 44. Each liner 42 and 44 is annular and includes amultinugget region 46 and a multihole region 48. Each multinugget region46 extends from dome assembly 32 downstream to each multihole region 48.

[0016] Liners 42 and 44 define combustion zone 36. Combustion zone 36extends from dome assembly 32 downstream to a turbine nozzle (notshown). Outer and inner liners 44 and 42 each include a plurality ofpanels 50 which include a series of steps 52, each of which form adistinct portion of combustor liner 40.

[0017] Outer liner 44 and inner liner 42 each include a bolt band 60 and62, respectively, and a first panel 64 and 66, respectively. Outer boltband 60 and inner bolt band 62 are positioned adjacent to dome assembly32 and extend downstream from dome assembly 32 to first panels 64 and66, respectively. First panels 64 and 66 are connected downstream frombolt bands 60 and 62, respectively. Each adjacent downstream panel 50 isnumbered sequentially, such that second panels 68 and 70 are connecteddownstream from respective first panels 64 and 66. Bolt bands 60 and 62include a plurality of openings 72 sized to receive fasteners 74therethrough. Fasteners 74 secure liners 42 and 44, bolt bands 60 and62, and a cowl assembly 78 to dome assembly 32.

[0018] Each combustor panel 50 includes a combustor liner surface 80, anexterior surface 82, and an overhang portion 84. Combustor liner surface80 extends from dome assembly 32 to the turbine nozzle. Combustor linersurface 80 and exterior surface 82 are connected together at overhangportion 84 and form a rear facing edge 86. A plurality of air coolingfeatures 88 separate adjacent combustor panels 50.

[0019] Air cooling features 88 include openings 90 which receive airtherethrough from an air plenum (not shown) such that a thin protectiveboundary of air is formed between high temperature combustion gases andcombustor liner surface 80. Furthermore, openings 90 permit convectivecooling of combustor liner 40. Specifically, openings 90 extend throughfeatures 88 which are formed between adjacent panels 50 and radiallyinward from nuggets 92 formed by panels 50. Panels 50 are connectedserially, such that each panel downstream end 100 is connected to anupstream end 102 of an adjacent downstream panel 50. Nuggets 92 areformed between adjacent connected panels respective downstream andupstream ends 100 and 102.

[0020] Liner multinugget region 46 includes a plurality of nuggets 92.In the exemplary embodiment, region 46 includes three nuggets 92. Linermultihole region 48 includes a plurality of openings (not shown).

[0021] A layer 110 of thermal barrier material is applied on combustorliner surface 80. Thermal barrier material further insulates combustorliner surface 80 from high temperature combustion gases. In an exemplaryembodiment, thermal barrier coating material is commercially availablefrom Englehart Industries, Wilmington Mass.

[0022] During operation, as atomized fuel is injecting into combustionzone 36 and ignited, heat is generated within zone 36. Although airenters combustion zone 36 through cooling features 88 and forms a thinprotective boundary of air along combustor liner surface 80, a variationin exposure of combustor liner surfaces to high temperatures may inducethermal stresses into panels 50. As a result of continued exposure tothermal stresses, over time, panels 50 may become deteriorated.

[0023] Deteriorated regions of combustor liner 40 may be removed andreplaced using the methods described herein. More specifically,deteriorated regions of either liner multinugget region 46 and/or linermultihole region 44 may be removed and replace using the methodsdescribed herein. If a field returned engine, such as engine 10,indicates that combustor liner multinugget region 46 includes at leastone deteriorated panel 50, a circumferential cut is made throughcombustor liner 40 to remove deteriorated panels 50. More specifically,as shown in FIG. 3, the cut is made radially through liner 40 andthrough a panel body 104, as illustrated with line 120, such that thecut extends from liner exterior surface 82 to liner interior surface 80,and such that a portion 122 of panel body 104 of panel 50 being cutremains secured within combustor 30. Furthermore, the cut is extendedthrough liner 40 downstream from deteriorated panels 50 being replaced.Fasteners 74 may be loosened to separate deteriorated panels 50 fromliner 40 for removal. Alternatively, a second cut may then be madeupstream from deteriorated panels 50 being replaced, such thatdeteriorated panels 50 are separated and removable from combustor liner40.

[0024] After deteriorated panels 50 are removed from combustor liners40, replacement panels (not shown) may be installed into combustorliners 42 and/or 44. The replacement panels are formed to include anugget configuration that is substantially identical to that portion ofliner 40 being replaced. In one embodiment, at least one of a forging,roll welded ring, or a casting is used as a replacement panel.

[0025] The replacement panel is then welded into combustor liner 42and/or 44, such that the replacement panel is welded to an existingpanel 50 that remains secured within combustor liner 42 and/or 44. Morespecifically, a downstream side (not shown) of a body of the replacementpanel is welded to panel body portion 122 within combustor 30. In oneembodiment, electron beam, EB, welding is used to secure the replacementpanel within combustor 30. In another embodiment, tungsten inert gas,TIG, welding is used to secure the replacement panel within combustor30. Thermal barrier coating material may then be applied on replacementpanel combustor liner surface 80, and fastener 74 is then re-tightened.

[0026] If a field returned engine, such as engine 10, indicates thatcombustor liner multihole region 48 includes at least one deterioratedpanel 50, a cut is made through combustor liner 40 to removedeteriorated panels 50. More specifically, as shown in FIG. 3, thecircumferential cut is made radially through liner 40 and through apanel body 104, as illustrated with line 120, such that the cut extendsfrom liner exterior surface 82 to liner surface 80, and such that panelbody portion 122 remains secured within combustor 30. Furthermore, thecut is extended through liner 40 downstream from deteriorated panels 50being replaced. A second cut may then be made within multihole region 48and upstream from deteriorated panels 50 being replaced, such that adeteriorated portion of multihole region 48 is separated and removablefrom combustor liner 40. Fasteners 74 may then be loosened to separatethe deteriorated portion and multinugget region 46 from liner 40 forremoval.

[0027] After deteriorated portions of multihole region 48 are removedfrom combustor 30, a replacement panel may be installed into combustor30. In one embodiment, at least one of a forging, roll welded ring, acasting, or a sheet metal panel is manufactured and used as areplacement panel. The multihole region openings may be formed after thereplacement panel is attached. In one embodiment, the openings areformed with a laser process. In another embodiment, the openings areformed using an electron discharge machining, EDM, process. In yetanother embodiment, the newly formed openings may be sized differently,reduced, or re-positioned, to facilitate improving cooling of combustor30.

[0028] The replacement panel is then welded to an existing panel 50 thatremains secured within combustor 30. More specifically, a downstreamside (not shown) of a body of the replacement panel is welded to panelbody portion 122 within combustor 30. In one embodiment, electron beam,EB, welding is used to secure the replacement panel within combustor 30.In another embodiment, tungsten inert gas, TIG, welding is used tosecure the replacement panel within combustor 30. Thermal barriermaterial may then be applied on replacement panel combustor linersurface 80.

[0029] Because deteriorated liners are replaced using the methoddescribed herein, combustors 30 are returned to service using areplacement process that facilitates improved savings in comparison toremoving and replacing entire combustor liners 40. Furthermore, becausethe replacement panels are formed to be substantially identical tooriginally installed panels 50, aerodynamic performance and combustorperformance are not adversely impacted by the replacement panels.

[0030]FIG. 4 is an enlarged cross-sectional view of an alternativeembodiment of an inner combustor liner 140 that may be used with gasturbine engine 10 (shown in FIG. 1). FIG. 5 is an enlarged plan view ofcombustor liner 140. Liner 140 is substantially similar to liner 40(shown in FIGS. 2 and 3), and is installed within a combustor (notshown). The combustor includes a combustor liner that includes annularinner liner 140 and an annular outer liner (not shown) that is formedsubstantially similarly to inner liner 140. Inner liner 140 includes aplurality of panels 150 which include a series of steps 152, each ofwhich form a distinct portion of combustor liner 140.

[0031] Panels 150 are connected serially. Inner liner 140 includes abolt band 160 and a first panel 164. Inner bolt band 160 is coupled to adome assembly (not shown) and extends downstream from the dome assemblyto first panels 164. First panel 164 and panels 150 are connectedserially downstream from bolt band 160, such that each adjacentdownstream panel 150 is numbered sequentially. Accordingly, a secondpanel 168 is connected downstream from first panel 164, and a thirdpanel 170 is connected downstream from second panel 168. Bolt band 160includes a plurality of openings 172 sized to receive fasteners 74(shown in FIG. 2) for securing liner 140 to the dome assembly.

[0032] Each combustor panel 150 includes a combustor liner surface 180,an exterior surface 182, and an overhang portion 184. Combustor linersurface 180 extends from the dome assembly to the turbine nozzle.Combustor liner surface 180 and exterior surface 182 are connectedtogether at overhang portion 184 and form a rear facing edge 186. Aplurality of air cooling features 188 separate adjacent combustor panels150.

[0033] Air cooling features 188 include a plurality of openings 190which receive air therethrough from an air plenum (not shown) such thata thin protective boundary of air is formed between high temperaturecombustion gases and combustor liner surface 180. Openings 190 are knownas dilution openings and extend between liner surface 180 and exteriorsurface 182 to facilitate cooling of the combustor gases. Additionalopenings 194, known as cooling holes, extend through each nugget 152.Specifically, openings 194 extend through features 188 which are formedbetween adjacent panels 150 and are radially inward from nuggets 152formed by panels 150. More specifically, each panel 150 includes anupstream end 200, a downstream end 202, and a body 204 extendingtherebetween. Panels 150 are connected serially, such that each paneldownstream end 202 is connected to an upstream end 200 of an adjacentdownstream panel 150. Nuggets 152 are formed between adjacent connectedpanels respective downstream and upstream ends 202 and 200. Nuggets 152are known as super slot nuggets. In the exemplary embodiment, liner 140includes six nuggets 152.

[0034] In an alternative embodiment, a layer of thermal barrier material(not shown) is applied on combustor liner surface 180, and insulatescombustor liner surface 180 from high temperature combustion gases.

[0035] Deteriorated regions of combustor liner 140 may be removed andreplaced using the methods described herein. If a field returned engine,such as engine 10, indicates that combustor liner 140 includes at leastone deteriorated panel 150, a circumferential cut is made throughcombustor liner 140 to remove deteriorated panels 150. Morespecifically, as shown in FIG. 4, the cut is made radially through liner140 and through a nugget 152, as illustrated with line 220, such thatthe cut extends from liner exterior surface 182 to liner surface 180. Inone embodiment, the cut is made between third panel 170 and a fourthpanel 222. Furthermore, the cut is extended through liner 140 downstreamfrom deteriorated panels 50 being replaced.

[0036] After deteriorated portions liner 140 are removed from thecombustor, a replacement panel (not shown) may be installed intocombustor liner 140. In one embodiment, at least one of a forging, rollwelded ring, a casting, or a sheet metal panel is manufactured and usedas a replacement panel.

[0037] The replacement panel is then welded into combustor liner 140,such that the replacement panel is welded to an existing panel 150 thatremains secured within the combustor. More specifically, a downstreamend (not shown) of the replacement panel is welded to an existing panel150 such that a nugget 152 is formed between the replacement panel andpanel 150. In one embodiment, electron beam, EB, welding is used tosecure the replacement panel within combustor liner 140. In anotherembodiment, tungsten inert gas, TIG, welding is used to secure thereplacement panel within combustor liner 140. Thermal barrier materialmay then be applied on replacement panel combustor liner surface 180.

[0038] The above-described combustor liner replacement method statorassembly is cost-effective and highly reliable. The method includes thesteps of removing deteriorated panels from the combustor liner, suchthat the deteriorated panels may be replaced with replacement panels. Inone embodiment, the deteriorated panels are removed by cutting throughthe body of the panel, and replacement panels are then welded to thebody of panels which remain attached within the combustor. In analternative embodiment, the deteriorated panels are removed by cuttingthrough a nugget downstream from the deteriorated panel, and replacementpanels are then welded to the existing panel such that a nugget isformed between the replacement panel and the existing panel. As aresult, a method is provided which enables deteriorated combustor linerpanels to be removed and replaced in a cost-effective and reliablemanner.

[0039] While the invention has been described in terms of variousspecific embodiments, those skilled in the art will recognize that theinvention can be practiced with modification within the spirit and scopeof the claims.

What is claimed is:
 1. A method for replacing a gas turbine enginecombustor liner panel, the combustor having a combustion zone formed byinner and outer liners, the inner and outer liners each including aseries of panels and a plurality of cooling features, the coolingfeatures formed by overhanging portions of the inner and outer linerpanels, the cooling features between adjacent panels, a plurality of thepanels including cooling nuggets, said method comprising the steps of:cutting through at least one panel nugget to remove at least one panelfrom the combustor; and installing at least one replacement panel intothe combustor such that the series of panels are arranged in stepsrelative to one another,
 2. A method in accordance with claim 1 whereineach panel includes an upstream end, a downstream end, and a bodyextending therebetween, said step of cutting through at least one panelnugget further comprising the step of cutting radially through at leastone of a panel upstream end and a panel downstream end
 3. A method inaccordance with claim 1 wherein said step of installing at least onereplacement panel further comprises the step of welding a replacementpanel to an existing panel secured within the combustor.
 4. A method inaccordance with claim 1 wherein each panel includes an upstream end, adownstream end, and a body extending therebetween, each nugget formedbetween adjacent panels, said step of cutting through at least one panelnugget, further comprising cutting between adjacent panels.
 5. A methodin accordance with claim 1 wherein said step of installing at least onereplacement panel further comprises the step of welding a downstream endof each replacement panel to at least one end of a respective panelsecured within the combustor.
 6. A method in accordance with claim 1wherein each panel includes an inner surface and an outer surface, saidmethod further comprising the step of applying thermal barrier materialto the inner surface of each replacement panel attached within thecombustor.
 7. A method for replacing a portion of a combustor linerwithin a gas turbine engine combustor, the combustor having a combustionzone formed by an inner and outer liner, the inner and outer liners eachincluding a series of panels and a plurality of nuggets, the nuggetsformed by adjacent panels, said method comprising the steps of: cuttingbetween an outer surface and an inner surface of at least one linerpanel nugget; removing at least one panel adjacent an area of the linercut; and installing a replacement panel into the combustor to replaceeach panel removed from the combustor.
 8. A method in accordance withclaim 7 wherein the combustor further includes an upstream end and adownstream end, a first panel coupled to the combustor upstream end witha bolt band, said step of cutting between an outer surface and an innersurface further comprising the step of cutting through a nugget formedbetween the third and fourth panels extending downstream from the boltband.
 9. A method in accordance with claim 8 wherein said step ofinstalling a replacement panel further comprises the step of weldingeach replacement panel to respective existing panels secured within thecombustor such that a nugget is formed between each respectivereplacement panel and existing panel.
 10. A method in accordance withclaim 7 wherein said step of installing a replacement panel furthercomprises the step of welding each replacement panel to respectiveexisting panels secured within the combustor.
 11. A method in accordancewith claim 10 wherein said step of welding each replacement panelfurther comprises the step of welding a portion of a replacement panelnugget to a respective portion an existing panel nugget secured withinthe combustor.
 12. A method in accordance with claim 7 furthercomprising the step of applying thermal barrier material to the innersurface of each replacement panel attached within the combustor.
 13. Amethod for replacing at least one deteriorated combustor liner panelwithin a gas turbine engine combustor including an annular linerincluding a multinugget region, a multihole region, and an innersurface, the liner including a plurality of nuggets, the multiholeregion extending downstream from the multinugget region, said methodcomprising the steps of: cutting through at least one nugget downstreamfrom the at least one deteriorated combustor liner panel to be replacedand within at least one of the liner multinugget region and the linermultihole region; removing the at least one deteriorated combustor linerpanel from the combustor; and welding at least one replacement panel toat least one existing panel within the combustor for each deterioratedcombustor liner panel removed.
 14. A method in accordance with claim 13wherein said step of welding at least one replacement liner furthercomprises the step of using at least one of an EB welding process, a TIGwelding process, and a TIB welding process to secure each replacementpanel to each respective existing panel within the combustor.
 15. Amethod in accordance with claim 14 wherein each panel includes anupstream end, a downstream end, and a body extending therebetween, saidstep of cutting through at least nugget further comprises the step ofcutting through a panel nugget within the liner multinugget region. 16.A method in accordance with claim 14 wherein each panel includes anupstream end, a downstream end, and a body extending therebetween, saidstep of cutting through at least one nugget further comprises the stepof cutting through at least one end of a panel.
 17. A method inaccordance with claim 14 further comprising the step of applying thermalbarrier material to the inner surface of each replacement panel weldedinto the combustor.